ENH: Is possible use rename for flatten MultiIndex?

[jesrael]

From SO:

df1 = (df.set_index(['Animal', df.groupby('Animal').cumcount().add(1)])
         .unstack()
         .sort_index(axis=1, level=1))
df1.columns = [f'{a}_{b}' for a, b in df1.columns]
df1 = df1.reset_index()
print (df1)
  Animal  Age_1 Color_1 Length_1  Age_2 Color_2 Length_2  Age_3 Color_3  \
0    Cat      1   Brown     50cm      2   White     60cm      3   Brown   
1    Dog      1   White     99cm      2   White    129cm      3   White   

  Length_3  
0     55cm  
1    105cm  

If I want chain flatten MultIindex for one line solution, is it possible? Now f-strings cannot chain with sort_index and reset_index (or not idea how).

Is possible implemented MultiIndex.to_flat_index for DataFrame ?

df1 = (df.set_index(['Animal', df.groupby('Animal').cumcount().add(1)])
         .unstack()
         .sort_index(axis=1, level=1)
         .to_flat_index(axis=1)
         .reset_index())

[TomAugspurger]

Can you add the code for defining df1?

The request here is for an NDFrame.to_flat_index, with the behavior of

df.index = df.index.to_flat_index()  # or .columns for axis=1

correct?

[jesrael]

Yes, something like MultiIndex.droplevel is also implemented Series.droplevel and DataFrame.droplevel